Plastic containers



Feb. 17, 1970 v P. DAVIS PLASTIC CONTAINERS Filed Nov. 21, 1968 UnitedStates Patent O US. Cl. 220-97 4 Claims ABSTRACT OF THE DISCLOSUREPlastic containers are provided of the injection molded type whichcomprise a side wall having a top edge and a bottom edge defining abottom plane with the side wall tapering generally outwardly from thebottom edge to the top edge. A transverse bottom wall is positionedabove the bottom plane to form a false bottom and meets the side wall atan inwardly extending rim portion of the side wall. A lower portion ofthe side wall extends directly below the inwardly extending rim portionwith the rim portion defining a stacking ledge in the side wall. Thetaper of the side wall is predetermined to prevent jamming of the sidewall when one container is stacked in another with the bottom edge ofone container resting on the stacking ledge and positioned over thelower edge of the second container.

BACKGROUND OF THE INVENTION Injection molded plastic tumblers, glassesand containers of various sorts have come into increasing use. Somedifficulties are encountered in the construction of such containers inconnection with stacking and nesting of the containers. Structuraldeficiencies often exist, particularly with false bottom containers,i.e., containers having transverse bottom walls spaced above the loweredge of the side wall. When stacking lugs are positioned on the insideof the side walls, due to the somewhat frangible nature of many plasticsused, the lugs tend to crack or chip when subjected to stress as when astack is dropped during handling or shipment. When the containers arenested so that the lower edge of the side wall rests directly on thebottom wall of an adjacent container in a stack, there is a possibilityof cracking or stressing the bottom wall at the junction between thebottom wall and the side wall.

It is an object of the present invention to provide a structurallystrong plastic container which can be efficiently stacked with similarcontainers.

SUMMARY OF THE INVENTION According to the invention, a plastic containercomprises a side wall defining a top edge and a bottom edge with theside wall having an integral inwardly extending rim portion. The bottomedge defines a bottom plane. The side wall tapers outwardly from bottomto top and a transverse bottom wall is positioned above the bottom planeto form a false bottom which meets the side wall at the rim portion. Alower portion of the side wall extends directly below the rim side wallportion with the rim portion defining a stacking ledge in the side wall.The taper of the side wall is predetermined to prevent jamming of theside wall of one container with the side wall of another identicalcontainer when the containers are stacked with the bottom edge of onecontainer resting on the stacking ledge and positioned over the loweredge.

Since the stacking ledge is directly above the lower portion of the sidewall, there is substantially no sheer stress tending either to separatethe rim portion from the main body of the side wall or to separate thebottom wall from the side wall when identical containers are PatentedFeb. 17, 1970 ice nested. Moreover, the present construction enablesease and e fiiciency of high speed production by conventional in ectionmolding procedures.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features andadvantages of the present invention will be better understood from thefollowing specification when read in connection with the accompanyingdrawings in which:

FIG. 1 is a cross sectional view taken through the central axis of apreferred embodiment of an injection molded plastic drinking glass ofthis invention; and

FIG. 2 is an enlarged fragmentary cross sectional view through a lowerportion of two such identical glasses.

DESCRIPTION OF PREFERRED EMBODIMENTS With reference now to the drawings,an injection molded plastic drinking glass is illustrated generally at10 in FIG. 1 and has an upwardly and outwardly extending continuousgenerally frustro-conical side wall 11 closed substantially near itsbottom by an integral bottom wall 12 to form an integral plasticcontainer.

The glass 10 is preferably formed by conventional injection moldingtechniques as an integral unit of clear polystyrene. In addition topolystyrene, other conventional injection molding plastics can be usedincluding but not limited to polyethylene, polypropylene, acrylates,polystyrene mixtures and copolymers with other synthetic organicmaterials such as rubbers to form impact polystyrene.

The side wall 11 preferably tapers upwardly and outwardly from itsbottom edge 13 to its top edge 14 both of which preferably lie inparallel planes with the side wall symmetrical about a central axis 15of the glass. The upward inclination of the side wall is predeterminedto prevent jamming of the side wall of one container with the side wallof another identical container when the containers are stacked with thebottom edge of one container resting on the stacking ledge as will bedescribed.

The side wall 11 has an upper portion 16 above the bottom wall 12 and alower portion 17 forming a base for the glass and lying below the bottomwall 12. Intermediate the upper and lower portions of the side wall isan integral rim portion 18 defining a gentle curve 19 on the outside ofthe glass.

The rim portion 18 defines a preferably continuous horizontal stackingledge 20' on the inside of the glass. The stacking ledge 20 ispositioned directly above the lower edge 13 when the glass is uprightand the wall portion 17 and rim portion 18 define a solid supportcolumn. In some cases, ledge 20 is slightly downwardly inclined towardthe cup axis and has a frustro-conical shape to aid in centering oneglass in another when stacked.

The stacking ledge 20 preferably has an inside diameter at an innercylindrical wall 21 less than the outside diameter of the lower sidewall portion 17 at the lower portion thereof denoted at 22. When twoidentical glasses 10 are stacked as illustrated in FIG. 2., pressures ofthe top glass on the lower glass are transmitted vertically throughsolid plastic to the bottom plane defined by the bottom edge 13. Thus,there is substantially no shearing stress tending to shear a portionlying below the stacking ledge from the main portion of the side wall.

The height of the ledge 20 above the bottom wall can vary greatly but ispreferably minimized in order to minimize nesting height of a column ofstacked glasses. Preferably the height above the bottom wall issufiicient to strengthen the cup at the junction of the bottom wall withthe side wall and may be in the order of at least A of an inch.

The bottom wall 12 shown preferably has a dome shape positioned toprovide a false bottom. Flat false bottoms can also be used.

In a preferred embodiment of this invention, the side wall 11 has asubstantially uniform thickness of 0.025 inch with a thicknes at the rimportion 18 of .05 inch and an upward inclination of 30 minutes from avertical axis. The height of the stacking ledge 20 is 0.063 inch. Theover-all height of the cup is 3.99 inches, the outside diameter at thetop is 2.9 inches and the diameter at the bottom is 2.040 inches.

While a specific embodiment of the present invention has been shown anddescribed, it should be understood that many variations are possible.For example, the height of the annular rim created on the inside of thecup which forms the substantially horizontal stacking ledge 20 can varyconsiderably as can the dimensions of the glass and the side wallthickness. In all cases, the side wall thickness is maintained withinthe range of from 0.01 to 0.60 inch and preferably 0.02 to 0.06 inchwith the exception of the rim portion 18 which preferably has a.thickness twice that of the side wall portion 16. In some cases, it isdesirable to form venting means on the rim portion to permit air passagefrom the top edge 14 to the space between bottom walls 12 of two stackedglasses. The vents can be simple indentations in the rim portionextending from ledge 20 to wall 21. The number and dimensions of suchvents if used are minimized to maintain the ledge substantiallycontinuous so as to maximize the area thereof available to counterimpact forces. In some cases, venting can be accomplished by providingindentations at edge 13, extending substantially radially through theside wall.

Thus, in some cases, a stacking ledge can be provided by a substantiallyuniform or decreased thickness side wall portion having an outerconfiguration following the contour of the inner surface such asprovided by ledge 20 and wall 21 and such configuration is includedwithin the scope of this invention. While the rim portion which formsthe stacking ledge of the preferred embodiment has a thickness greaterthan the thickness of other portions of the side wall, the rim portiondoes not have to have increased side wall thickness.

What is claimed is:

1. A one-piece, injection molded, solid plastic container comprising,

a sidewall having a top edge, a bottom edge defining a bottom plane anda rim portion between said top edge and said bottom plane,

said sidewall being inclined upwardly and outwardly from bottom to top,

a lower portion of said side wall extending directly below said rimportion and having a thickness forming a solid support column with saidrim portion,

a transverse bottom wall positioned above said bottom plane to form afalse bottom meeting said side wall at said rim portion,

said rim portion defining a stacking ledge in said side wall axiallyspaced from said bottom wall and lying directly above said solid supportcolumn,

the inclination of said side wall being predetermined to prevent jammingof the side wall of one container with the side wall of anotheridentical container when said containers are stacked with the bottomedge of said one container resting on the stacking ledge of the othercontainer and positioned over the bottom edge of said other containerwhereby forces exerted by said bottom edge of said one container aretransmitted directly through solid plastic to said bottom edge of saidother container.

2. An integral plastic container in accordance with claim 1 wherein saidside wall has a thickness in the range of from 0.02 to 0.60 inch.

3. A plastic container in accordance with claim 2 wherein said rimportion defines a continuous annular stacking ledge lying substantiallyin a plane perpendicular to the axis of said container.

4. An integral plastic container in accordance with claim 3 wherein saidtransverse bottom wall is upwardly domed.

References Cited UNITED STATES PATENTS 2,805,790 9/ 1957 Smucker 220973,059,810 10/1962 Edwards 229-15 X 3,363,820 1/1968 Schilling 2291.5

GEORGE E. LOWRANCE, Primary Examiner US. Cl. X.R. 2291.5

